I am implementing a Low-power design with Power switches and Isolation cells. I have a CPF file that I commit and I can see that isolation cells and level shifters are inserted into the design correctly as I intended.
However, whenever I run optDesign, whether it be preCTS, postCTS or postRoute, Encounter seem to mark level shifters and isolation instances as don't touch instances and does not optimize them. As a result, the drive strength of the isolation instances are too small. I know that Encounter doesn't optimize clock nets but there is a ckECO option to take care of clock optimization. Is there a way to make Encounter optimize the level shifter and isolation instances and/or remove the dont touch marking on these instances?
Below are the messages I get in the log file when I run optDesign :
*info: Marking 12 level shifter instances dont touch
*info: Marking 64 isolation instances dont touch
I've tried to use set_dont_touch and set_interactive_constraint_mode options to override this but haven't succeeded so far. Has anybody gotten the same problem and does anybody know how to solve this?